GROUNDWATER
Groundwater The Hydrologic Cycle
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Groundwater Phreatic zone Vadose zone porosity
Groundwater Phreatic zone
Groundwater Porosity vs. Permeability: Porosity – the amount of water a rock can hold Porosity – the amount of water a rock can hold Permeability – the amount of water that can move through a rock in a given amount of time Permeability – the amount of water that can move through a rock in a given amount of time Which is more important?
Groundwater What is an aquifer? a layer of rock from which water can be easily extracted A layer of rock through which water does not move readily is called an aquitard or aquiclude
Groundwater An unconfined aquifer
Groundwater A confined (artesian) system
Groundwater How fast does groundwater move? Between: 1 meter/day, and 1 meter/year On average, ~ 10 cm/day What are the consequences of this slow movement?
Groundwater Artificial recharge ponds, N. California
Groundwater How does groundwater erode? Solution channels in limestone, England Groundwater can only erode by dissolution, usually helped by carbonic acid. Limestones are particularly susceptible
Groundwater An area dominated by groundwater erosion is called karst topography
Groundwater Evolution of cave system
Groundwater Satellite image of a karst terrain
Groundwater Areceibo, Puerto Rico – SETI radio antenna
Groundwater Sinkholes
Groundwater Winter Park, FL
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Groundwater Sinkhole swallows 2 cars, St. Louis, November 26, 2007
Groundwater Karst towers, China
Groundwater The Stone Forest, China
Groundwater Infilled sinkholes
Groundwater Red paleosols (Molas Fm) in Leadville Ls, Molas Lake
Groundwater How does groundwater transport its sediment? Only one way, in solution. This is what makes hard water, but dissolved load typically only in parts per million (ppm)
Groundwater How does groundwater deposit its sediment? By precipitation. This may occur within pore spaces, helping lithify sediments, or in open spaces as dripstone
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Groundwater Gypsum stalactites, Lechuguilla, NM
Groundwater Calcite cement in sandstone
Groundwater SiO 2 carried by groundwater replaces trees
Groundwater Types of groundwater: meteoric meteoric connate connate magmatic magmatic Any of the above may also be hydrothermal water
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Groundwater Issues with groundwater use: Pros: agricultural, industrial, & agricultural, industrial, & domestic water geothermal energy geothermal energy natural filtration natural filtration Cons: ground subsidence ground subsidence depletion depletion pollution pollution salt water encroachment salt water encroachment
Groundwater Groundwater use by state
Groundwater Geothermal test well, Nevada
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Groundwater Subsidence due to groundwater extraction, Mexico City
Groundwater Subsidence due to groundwater extraction, San Joaquin Valley, CA
Groundwater Salt water encroachment